In a variety of well testing, well clean-up, and flow applications, recovered fluids can be directed up from a subterranean location and/or other fluids can be directed down into a well for various testing, production, cleaning and service procedures. The flowing fluids often contain multiphase fluids, and require various choke manifolds to be used in an attempt to regulate the fluid flow. The choke manifold or manifolds may be positioned at a surface location, or downhole, and comprise fluid passages for routing the fluid through appropriate choke circuits.
Convention choke manifold systems often comprise a set of high-pressure valves and associated piping that define at least two choke circuits in which two adjustable chokes are arranged such that one adjustable choke may be isolated and taken out of service for repair and refurbishment while well flow is directed through the other adjustable choke. The choke circuit also typically includes a fixed choke, which enables regulation of a calibrated flow.
The adjustable choke, also referred to as a choke bean, contains a replaceable insert, or bean, made from hardened steel or similar durable material that can be changed to adjust the flow rate. The insert is manufactured with a precise diameter hole that forms the choke through which all fluids must pass. Choke inserts are available in a complete range of sizes, generally identified by choke diameter stated in 64ths of an inch; for example, a “32 bean” is equivalent to a ½-in. choke diameter. The adjustable choke typically does not allow an accurate choke size due to the complex geometry of the flow around the choke bean. Consequently, the design creates difficulty in controlling the flow area through the orifice.
Additionally, the choke bean design is extremely sensitive to erosion and can be completely destroyed in only a few minutes if the well produces sand, debris, proppant or other particulates with high-speed flows through the choke. Changing of the fixed choke size, however, also can create substantial difficulty and requires opening of the system while flowing. This approach can be time-consuming and induce HSE concerns related to pressures and deleterious constituents, such as H2S. Furthermore, fixed chokes can be plugged by large solids that become stuck in the orifice and block flow.